SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b73197f16696afacd765996c3fd9d62269ae9dceae9521c7b5f88feea4fec739' 
  AND token = '4f7tOXrdDtIsjx9i+g14mQ6J8ytOQ33zqUS1NJPxLHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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