SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a890774eae7015b76841bfaefc3be298e2b2cdaf5f91608eb2fe4f4631ce0aef' 
  AND token = 'igcWDPb3zCATSlK6ejCk2yVfgAbLZUF+Jzvl3E+k8Lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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