SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b709600f7b9e3a4389bdac7cc04841769737a41e21f680bfa11af6404f98fac9' 
  AND token = 'hbZEHTZSKQ6eXfuseZhbNxJJYpz/cW/298iCY4EKisc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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