SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6423abfe3f49646baabd79a4e067db2f781e70507219fcfdfe04535dbd2dc246' 
  AND token = 'DrHznPvv+ObFAaAlwOdeAHsfXt4hUF0Umlqfo39aKYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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