SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8be88d45c17299ef552a3c584771b28fcbc26287d449e0f1e233e8ed95331d5a' 
  AND token = '1G+Y0nbJZVhWTijfKV87a2fEkBDOu9xiZloaEraU4o0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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