SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8ad396c94d50e09d98b8fd5e2f39f1461c666fc2335d29df52b2887daefac61' 
  AND token = 'BJpHSpoXEXoS5TS/Wx//aJyign6CClJjyngnGJGVp44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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