SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3116bd93a3b2bb6b68e0fef532fbcd6d4301138c468862ab69975df3643c547' 
  AND token = 'l5frTGAiQ+Y52kbnkDRbgwJ1Vzm/b+Yl++uxKROrYBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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