SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '2510479c68845e011e470e326be88987098cf5ab93a8134f204b742b133283bc' 
  AND token = 'ZON6JYLliSCGdpiALp0dajxgwKdWzu46lW/EuUauyA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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