SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ac312477dc77fd8334b0d09a6f50519a04cfe1355455cbee2e4f212605e276a' 
  AND token = 'Qb3kuwdhvMfaY3wz8PBHJXgGAxFOufvvbBmr+2FkWKw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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