SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a23e58e006c31980305899c33e32b39bd477a1f566bd4166193a25fc693a26d2' 
  AND token = 'QPG7rzZcF72Gbboe0u2LgYWTiD8jNUXmu2RsaCh2ync=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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