SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd7e8dcd97823d6a1d3e0cec1476d92a524856b3a9dea78ce56a951d61032a0' 
  AND token = 'l3i5KvlPKXa9bjO5YtyXIswDdn3xiAcIRFpFlSjLG9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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