SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '409ddfdc6f200eabc2ee34dba0e23a863252598591f5a17e15275c293f3412fd' 
  AND token = 'UbigmFtQem40r/Q80ixzXQykg+uOkwmM3bPk69rYPac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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