SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b0e0783fb07f743444c749aeedf11e7959e8ffa27765774b2444d69a2062c13' 
  AND token = '9IquUDHujZe0OKXgardj5Yl/BQ3ouWNeJ96J/mzKdwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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