SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbce67f87664238c47f1525a006e2a7b6eb27d49e258c7a16108f6afdc754e69' 
  AND token = 'rKj0G7xSx2BT+jhMs90Eq9MHnJvMpI+SByNs1/UJuPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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