SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfe149413feeae6c7e7026515864c4ddf5fdf18f96efdad4905f537d5812f33c' 
  AND token = 'lPY8glIPvaqQOiw6Mkhr2iGrLIHuLRaqf1v+K/DeDpE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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