SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b4322f3e8db495bd5820d80d3e8a3a3ffd2ddba93e1c3749aca87f6c2828621' 
  AND token = 'dfAh1aBU1QqNfRTbqiVgPFCVGbqbLPN5bh9jvRt1lHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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