SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76188e5daf7f19fae214c2e98012166ce80892ed7f06a77a391111f3d1a75874' 
  AND token = 'ml8Hny8EurrbEpJwajuXnjZQOZNrQIZGfK2NvvSMKxU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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