SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3caf55aa69012e878e3aaf21527cfb03bef6d15de44ce6f2da366ad9f4941958' 
  AND token = 'NPSZnZ8NnscCqB/14OW1FgGvm0tXVbgcBBb+GvErq3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00062

JSON explain

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