SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '324bd4861618de4c31803eed3dd6d9e8b60f128b1812a28d23e29afff2178159' 
  AND token = 'x56jeeEW6HTzcpFubMkNjPvDF56+nTL39+wGog0q0Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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