SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '607df91aae800af760d30def07f7f048a1c175afd7c40ee91c98b91289728c12' 
  AND token = 'CWO2+NUm20gBE/tNU155yr6HnpsQF6m4iw7OsGtlMDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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