SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fa9a668fc1091610c9d2bcaeabc36887a4fda70d9cda3335cb68ec1a80afd41' 
  AND token = 'TZAv4ePqSC9qxV9ql9wurL7pAb4zk/xYV3Sfi9aYDyY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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