SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4a27347aae6ef5a137a0fc1d1a1313df14424486bab91d5eff39d061ce2c0c6' 
  AND token = 'A3LtDHB9dikfMdRRPRs7FsHjVnBOW4XHhfDsNjTvuDE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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