SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78bc73a963c5abea80609da6ba623f20586d15598e4c6e2bd347630f740d55fc' 
  AND token = '1gz8DORw6cVje//cXDjLsOCNxZqKdmB6cbT3J/v4EcQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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