SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'b1875be7f40290b997a826196e07ca5bf9bdcb86119cceab43ed528158bbd952' 
  AND token = 'u2srYQagwpnRHT7dg4z1gSAuJNeIyecyBNwnDsoYbxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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