SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db68282457734b25e81d35c9489034bb3a8098df72e408f8d5789013f792888d' 
  AND token = 'HTdVs4DV+7jvl9SoUgW6YEPmhmY1Z+SRVmPB2UBzzgE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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