SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8eab171eda1180fae40a407f40155ab9be07d3b4302a2a3be5a2031482ec9816' 
  AND token = '8F8PnJcnr9OQFZtYxPsGgDex0p+FjzDzO5nTTxxwvJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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