SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a7690409d904bea99179912153250fa32501253b3f8f2ab1e7f25c586c6872a' 
  AND token = 'MnyuxU5oxbTaAKYFclSmuqTOjT5nD8+ImiWAVLso+JM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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