SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cdf8ab3b1c6264212b304920586cc898ab9a4547feefdab071e1fa06a88c39cd' 
  AND token = 'jJMa3wuYXQkoUQ6jGLmRPzq2WKJbOEXgJjVK9xefSSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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