SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e780aed4c5532bdd1560e1d09c681609c52791a19232749bf41980f3fc9b255' 
  AND token = '+SqIwhS3tJw+dhugdMYuEv0uceFrncPI4mZYtks/KuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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