SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5c9703f707ce641dac5226a6ae2471bec53343e53e202adc66ae7b47fb88d3e' 
  AND token = 'olut/9mjpzqROhfXUxX/9dwrvDbg5nMgWBlR9CW+eFw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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