SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b414f7458e33095a5f876d4f6ccb42029808c9371d84385d06edf83b0902800' 
  AND token = 'QyllU9onlzwk8nd+zHApGUu7rJ4FdkMIMNRlsWD2LBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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