SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56be40aa5ff1cd3c8440b204c745761edc8f3b1ebebaa0247bb8c68649cdb306' 
  AND token = 'kQBMoGpIrlT+Dw/7faX7NUSBIKQfV08HIoORMQEaoco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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