SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad33ef71d4611cf6b90df4781d299c56df15822a7a04853865ccded9a5a8ea65' 
  AND token = '+66hbWforUdqwnrHOLCGL/t8bMPujDtx/AUK4xtp2vw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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