SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68546f8b3ea2c0caeb07586228650feb7733cec2acd46230b941b28e5cf51563' 
  AND token = 'bFZdXuDn6qrnkrU4XWhIebLe+ReDs0OQLukfYf+8vKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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