SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '04f08059d8b4201b1bd66f55e04fd72d2ddc9ee10fb16778b6eb4dede5efa343' 
  AND token = 'EH+rnc4RbvcU3orIxJ0WKlUBs6JdognLMpkeFn51XLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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