SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5a2acdae76b78becbbb020121a87291ce3494b8650d2abda1f004ed757c6298' 
  AND token = 'N7zIyCHLwfTnMbKMVVKCKWvlIjoMRiL6tiUJFZfDzEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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