SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339d01cddd435da67d5cb3d63816673fc92af5dd0325669adb8dfd0bc20ca99f' 
  AND token = '8l9UBBW0Pq7Yjlq1s9WylQ6cfe9MC7JgoxGjCSWp1Xk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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