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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42273caf26da19283b61257da3747e3a16804012f5fd6631b2feb1d0bc9ef9dd' 
  AND token = 'DYSip7V6omAnQHB3EwIsmE6dNI8tNhAJB3TdPWq7BdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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