SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9eb322fbea7b0d920e55fde68115ca9493be01751452d4f3eb8b7221fdbb586' 
  AND token = 'fVPFaBAzQTs8VA9Jrppcaclu7ykIiI+sGZtIBzKen70=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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