SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3771680dfe88434a721260b43b81edf1f1fab9158e4ad45602aa044f9d6d6b57' 
  AND token = 'uVBh8PJxljvXzilhz9UWSi/sMRSJdVDBxbd6PKOfvn0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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