SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0375118871e93b691aafdf03ccd8818dde189734ab47612249d397d222ae1cd3' 
  AND token = 'FCXjDivbXhVfWG4wOEUNUpoxUiLqEb9HcnzgRgRucJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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