SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a36120e038d93c76c8db573e35749e7b7e34ea37281cd964c8b619ff3db18335' 
  AND token = 'UJGlIfDvh+3FRUzKDa691+NYBobMH44AUNKhdHBXJ+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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