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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4ccd84d9f2c439eacafacddf36829138f4d2fe3d3929d6f49c41ddce453d261' 
  AND token = 'fRXOcY0G3Yt0qlwruPlE6bgth9SnHfSHngeZdQ5pUKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}