SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '187380eb4337717c7d1e4ffd2b43d94285199a88979f94a31784c663a2b47706' 
  AND token = '8Ml06m4ngGqgtIfbFVL4lBYFobUqofOjpheIxHWfvWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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