SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6b96212548c9025f9f9ff6a10a8a3fcada72dc610e94a53d9ac0c5282c0fd4f' 
  AND token = 'WOT8B3PzXs0uSaCXc0HO1vBlHVIlA8wSXU5K0bi/jeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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