SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6db1e0e884e8139c78394b822d5f63b31778563441c330cb6708c6bb52b03fa6' 
  AND token = 'xqJ2FFD7K8asmQUQvhRp4RV/OCMW1sKI3YqRBrRqUts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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