SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75a95f17b90d91e6672af260f9aa239722c7d031234a320a20dba4dc355cf6b' 
  AND token = 'IgJhH5EnQvvs4luEvTWwV47LtbuAjuPj8stBqerWzCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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