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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71aa324199a290d6e77e7a3655183668fc25ab1d75b7f2e588fd804f1c0a6a79' 
  AND token = '8CcwR/+Lv//7wvrtPuq4UDiSGO914MhW39/dOfAwl6g=' 
  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"
    }
  }
}