SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2adaee6a642f21e87f701b6aa8481de5a23f751b3a1edb08e506fd37c92d483d' 
  AND token = '4L4l75U695MG6vyfMvPcf/9blGz0263I1tkuVcc03Dg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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