SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'af87793c41d782a6a41d4b43a0a60f0d07d78fee1587a1999764b92350f44708' 
  AND token = 'KlcR1Z4nLgXA7XppWOOhkhyLpRBYF8+7gNVT+X2GE1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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