SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9ed0596ba2620dff199e5c87fc086e36a46876aa822ce65afa5deda69b116dc' 
  AND token = 'YzKqmnlnmnxvTeMWwOusc2bYcUwSmtbRIHplNBpFzNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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