SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc3435541549323f68a56d00270e8378f4954170250d4327a655f6ba0e8daa38' 
  AND token = 'L2V42khu8llY3Ro7UQdYV+GvbzPojqSydTtDV2zISdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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