SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96337a99c5176d9e0b46bacd83f8c85e6e1a7f385d22d584a017964be69e3b3e' 
  AND token = 'f9u4VZQa13ZNO4HEbPmk6i5Cb1mC2q+S4We/3n0AI88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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