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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5aa483d81ed3b7997d07d25bace8c602915d55e049d993d850e2653613ec787' 
  AND token = 'ykSuj+9z5WhUvbvnR4aNqDpxTOqVQsuuNztuy8i2j0o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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