SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50454b21d369325b5f2f4ec2000857b6889d19ef4f85e7604e4d7cf52951803e' 
  AND token = 'KN3wdl/Bi2zxVPuq8GeYuPMkiF6c1mH+1QJCoUd5wHk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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