SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b51dc1cda9a568c93c2347a810845dab52e2c58d835297277586a37db8d5cd4' 
  AND token = 'B7pgbfeSb158KdGqNTe8DKwL1QWBYs7zpPdsr3XsV4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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