SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe48f2f6566647a72a377a2779139f55f86d3d1713d4898f71aa8a61124eedbb' 
  AND token = '+4JT2Hs5JYGl8qddnAjnZUQSMXUt83OrWs1Yp6BxXXw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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