SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a113569ef8e8a262c0add86cece235a0519989953e7f3ae16804567f952e397' 
  AND token = 'k7gK8IamYmJckcQxqDFKk7ff9ZbJobWwapjufahRmIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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