SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d5378c0063bb66af55bc9dc464dd4ae3222c351bc990837222092c1975f67c8' 
  AND token = 'JrdqCu7YxD/NKM4iByYQ9XjQ6FjZ0rXQZUVriM6wM+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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