SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '984360875c6b56240d8a055a73e1f87e759c701f82777d633b70d8463ce63652' 
  AND token = 'CCYoWjrbWObdn7tKkEL7w4SkGtUgbsLQgZbnW6S+f6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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