SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b6df34e313aedc7347c948bc1a842b83b280f410af18dcc8661444bab72b339' 
  AND token = 'pZG7AYV1PavCJ3upb+tvflYsBAArPx0tvVNCjq4FAiQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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