SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '456321ad9af4c921524d447aeab4dc33d51e5b8edaaa6a165a8b7fa0da27b342' 
  AND token = 'cCGcxmZ++/WuyL6Ez1/yhGqEgvJ883hIdeFgYgRWPuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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