SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '209bffcd97da401023a1416dad83dfe0b557c15d09a8d3dd79156fb86151f209' 
  AND token = '3vGWIAkRLYG3ZfogINa+pzzH8V3z7WHY44+6QD5Y4wc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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