SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03337b1712cfda645c6f1bc2169acffae550559d751d03013e40864874dba738' 
  AND token = 'd/RekQTmps7XVTCHfMrKrSO74Pqwj4btqXDYUmbjbB4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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