SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b15fdf76a2ee63b43b0295058d54c1cbe76982940cdfe35d9a29616da96c004' 
  AND token = 'jgcLMSS/THsUO0zFLIVVzS7glKC/NtYGZDSpSYgK0/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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