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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8849de1d1004c14b4fd3d3fb142c680f9638702f6e59aedc1eeb22c7c2c4d6c' 
  AND token = 'MoWfbEknf5XCsjlyprhQ2NS1NfZTPvZR7t8wk0VmZgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}